Gordon Brown today revealed plans for tougher than expected legal action against bankers' bonuses and a promise to enshrine in law a halving of the government deficit by 2014.

Treasury sources initially gave little detail on how these two new centrepieces of the next Queen's speech would work, and there was scepticism that Brown was planning anything other than a stronger rhetorical assault on bankers, although in practice rhetoric may force the City to rein in what could be a politically charged round of huge bonuses this Christmas.

In his interview on BBC1's Andrew Marr Show, Brown gave the impression that he was determined to go further than previously to clamp down on bonuses, saying he had been struck at the meeting of the G20 leaders' meeting in Pittsburgh by the extent to which bankers had not understood the need for responsibility. He even promised that British legislation against bankers will be the toughest in the world.

Ministers have long set their face against a cap on bankers' bonuses, saying they are unworkable, arguing instead the focus should be a clawback and a deferral of bonuses to ensure that growth inside the company is sustainable.

The G20 in its communique went further than some expected, saying it would impose "strong international compensation standards".

It agreed that it is essential that banks should prioritise using high profits to rebuild their capital base to support lending and reduce risks. Dividend payments should be consistent with this policy. Regulators, as a result would have a legitimate interest in banks' aggregate bonus rates where these have implications for their capital position.

It has also been notable that the rhetorical onslaught against the bankers has been raised by Brown's City regulators. Lord Myners, the City minister, in a speech on 18 September, and Lord Turner, the chairman of the Financial Services Authority in a speech on 22 September, insisted the risk structure of bankers' bonuses was not the only issue at hand; there was also the overall level of payments.

Myners in particular argued that bankers had to ask themselves why some traders were taking home £10m in a deal when the average wage in Britain was only £20,000. He complained the labour market in the City did not seem to be working.

It may be that as the shadow chancellor, George Osborne, has warned, ministers are worried City bonuses are likely to be very large this December, and fear their rhetorical warnings to bankers would look hollow unless they ratchet up the pressure. Now Alistair Darling, the chancellor, in combination with the French finance minister, Christine Lagarde, will call in the bankers and tell them to abide by the guidelines agreed at Pittsburgh.

Turner pointed out that banks' current high profits, and hence bonuses, were not due to the fundamental skills of bankers. He put the profits down to "a set of specific post-crash circumstances: increases in the market share of the survivors; government guarantees and central bank liquidity support; very low interest rates; volatility; and large government debt issues".

There is even less detail available on how the government plans to make its deficit reduction target a legal obligation on ministers.

The new requirement to bring debt down as a proportion of GDP is likely to be monitored by the National Audit Office.

A legal requirement to cut debt will restrict ministers' freedom to spend, and is clearly designed to reassure voters that Labour realises the spending blitz is over.